The present invention relates to a pressure reducing valve for vehicle hydraulic brake systems for reducing the pressure by means of a stepped piston above a certain pressure (switching pressure). When the switching pressure is attained at least one connecting channel between inlet and outlet is blocked by a sealing body closing the inlet end of the connecting channel.
A pressure reducing valve of this type is intended to reduce the brake pressure acting on the rear wheels in the zone above the switch pressure in order to thus adapt the brake force to the dynamic axle load removal at higher brake decelerations. In a known pressure reducing valve of this type disclosed in German Patent DT-AS No. 1,505,448 the changeover device which is responsive to the switching pressure is designed as a spring-actuated valve comprising a valve body, a sealing body and a valve spring. The valve is adapted to leave its closed position only if the supply pressure is still further increased following closing. The known pressure reducing valve is not in a position to obey a reduction in the supply pressure immediately after closing, i.e. after the change-over to pressure reduction has occurred. If used in a rear-axle brake circuit, the rear-axle braking action will be maintained, even if the operator would like to reduce the braking action precisely in that particular instance.